The disclosure concerns a method to exchange printing substrate rolls in a printer in which a first printing substrate web unwound from a first printing substrate roll is printed to with ink with the aid of at least one print head, and in which the first printing substrate roll is exchanged for a second printing substrate roll.
In high-capacity inkjet printers, printing substrate webs, in particular paper webs, unwound from printing substrate rolls are often printed to with ink via the printer. The printing substrate rolls must hereby inevitably be exchanged regularly, at the least when the printing substrate supply runs out. During the exchange of the printing substrate rolls, the printing is typically stopped, meaning that no ink is ejected from the nozzles of the print head during the exchange. It is problematic with this that, in particular in areas with a warm, dry climate, the print heads may dry up very quickly if no printing takes place. This has the consequence that individual nozzles may plug if the exchange of the printing substrate rolls takes too long, and a high-quality print image is thus no longer possible.
A known method to avoid this problem is that a cleaning process of the print heads is first executed in order to remove dried ink after the exchange of the printing substrate roll, before the actual printing operation is begun again. However, this is disadvantageous in that it is linked with an additional cost, and the downtime of the printer is hereby increased.
U.S. Pat. No. 4,970,527 describes a printer with a microcontroller with the aid of which the time that has passed since the last utilization of the print head is determined. If a preset threshold of no printing is exceeded, a predetermined quantity of ink is ejected from all nozzles of the print head in order to prevent a drying.
U.S. Pat. No. 6,619,784 describes a method in which it is determined when ink containing colorant has accumulated in the region of the nozzles. In this case, this ink is printed onto the printing substrate in a region outside of the actual print region.
EP 1 223 134 A2 describes an on-the-fly roll exchange in a printer, meaning that one printing substrate roll is replaced with another printing substrate roll without the printer needing to be stopped for this. Even given such exchanges of rolls on the fly, it is customary to not print during the exchange, meaning that no printing takes place while that region in which the two printing substrate webs are glued to one another is directed past the print head.
A method for exchanging printing substrate rolls in a printer is known from the document WO 2007/114813 A1, in which method the print job continues to be printed in the transition region between the printing substrate rolls.
Additional methods to exchange printing substrate rolls in a printer, and corresponding printers, are known from the documents US 2014/0035982 A1, JP 2012/153150 A and JP 2012/166557 A.
The exemplary embodiments of the present disclosure will be described with reference to the accompanying drawing.